A microscopic view of Casacius physical bitcoins

[casascius]

I have seen photos lose their color fidelity over the years, but have you ever seen old documents turn into blank paper? Me neither.

[1715534977]

1715534977

[1715534977]

1715534977

[1715534977]

1715534977

[spiccioli]

I have seen photos lose their color fidelity over the years, but have you ever seen old documents turn into blank paper? Me neither.

casascius,

I have some of your coins and I was really wondering how long I can expect to be able to read them.

I was not trying to scare anyone.

Do you print them or do you write them by hand? What kind of ink do you use?

spiccioli

[casascius]

Do you print them or do you write them by hand? What kind of ink do you use?

They are inkjet-printed, and I processed the private keys entirely myself.  Inkjet was deliberately chosen over several potential other possibilities including laser printing, thermal printing, dye sublimation, and laser engraving (all of which are available to me), with security and longevity being primary concerns.

The inkjet used to print the private keys is different from the inkjet on the outside of the series 1 coins.

If somehow the inkjet began to fade over time, we'd start to discover this as people opened their coins for redemption, long before the blacks would fade to white (assuming such was possible).

As for whether I'd write them by hand, no way - that would be egregious both in terms of difficulty and possibility for transcription mistakes.  However, I did inspect every single sheet of keys (330/sheet) by hand to ensure complete and legible printing, proper alignment, proper front-to-back registration and key correlation (public/private), as well as completeness of the print job without any duplications.  They are then laser-cut into circles.  So I am totally confident that every single key circle is good, and have no shivers about sending (for example) 1000 BTC to one of them when one goes in a gold coin.

[spiccioli]

Do you print them or do you write them by hand? What kind of ink do you use?

They are inkjet-printed, and I processed the private keys entirely myself.  Inkjet was deliberately chosen over several potential other possibilities including laser printing, thermal printing, dye sublimation, and laser engraving (all of which are available to me), with security and longevity being primary concerns.

The inkjet used to print the private keys is different from the inkjet on the outside of the series 1 coins.

If somehow the inkjet began to fade over time, we'd start to discover this as people opened their coins for redemption, long before the blacks would fade to white (assuming such was possible).

As for whether I'd write them by hand, no way - that would be egregious both in terms of difficulty and possibility for transcription mistakes.  However, I did inspect every single sheet of keys (330/sheet) by hand to ensure complete and legible printing, proper alignment, proper front-to-back registration and key correlation (public/private), as well as completeness of the print job without any duplications.  They are then laser-cut into circles.  So I am totally confident that every single key circle is good, and have no shivers about sending (for example) 1000 BTC to one of them when one goes in a gold coin.

casascius,

thanks for the explanation!

spiccioli

[JMAHH]

+1

[squid]

As a graduate student with access to high resolution microscopes and an SEM I am tempted to buy one of these just to examine it.

[JMAHH]

As a graduate student with access to high resolution microscopes and an SEM I am tempted to buy one of these just to examine it.

DO IT

[casascius]

As a graduate student with access to high resolution microscopes and an SEM I am tempted to buy one of these just to examine it.

If you examine one and post your findings I will reimburse the cost of one coin plus shipping.

[squid]

As a graduate student with access to high resolution microscopes and an SEM I am tempted to buy one of these just to examine it.

If you examine one and post your findings I will reimburse the cost of one coin plus shipping.

Do you have a coin denomination in particular you'd like examined? Otherwise I will just look at the gen2 1 btc coin

[Michael_S]

I read about these physical bitcoins only now - I think it is a nice concept to make bitcoin a bit more tangible and spread it further, and of course it could be used in offline transactions for small amounts.

Two question to Mike, both not crucially important, I am just asking for curiosity:

First, the Casascius 10 BTC Silver Round (http://casascius.appspot.com/group?type=5) has 3 circles of seemingly random 0s and 1s around it (visible even w/o microscope ;-) ). Is it really random, or does this sequence of bits carry any hidden message/meaning (byte code, morse code or whatever)? It would surprise me if these carefully and well-designed coins did not carry any meaning in this bit sequence...

Secondly, what does the nickname "casascius" stand for? At least it is not easy to remember, I always have to concentrate to avoid mistyping it.

[quasarbtc]

Nice images. Not bad for the money.

[Foxpup]

First, the Casascius 10 BTC Silver Round (http://casascius.appspot.com/group?type=5) has 3 circles of seemingly random 0s and 1s around it (visible even w/o microscope ;-) ). Is it really random, or does this sequence of bits carry any hidden message/meaning (byte code, morse code or whatever)? It would surprise me if these carefully and well-designed coins did not carry any meaning in this bit sequence...

It's ASCII for "Bitcoin: an idea too big to fail". The BTC25 coin has a similar message that reads "You asked for change, we gave you coins".

[Domrada]

given the recent renewed interest in casascius coins, i thought this thread deserved a bump... yw.